@Horus Lupercal will show you what is a very big rocket.
If she were made of rock, it technically would classify as a mountain. At 1700 metres tall, a UK based assembly and launch would have it as the largest single object, man made or natural, building or terrain feature, on the entire British Isles.
I present a pretty large rocket, the Komodo
One of these days
Altaïr, I'm gonna get onto 1.5, put your launcher launcher ontop of this and see how far I can throw it.